Monthly Archives: June 2015

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The dream of a cleaner, greener transportation future burns brightly in the promise of hydrogen-fueled, internal combustion engine automobiles. Modern-day versions of such vehicles run hot, finish clean and produce only pure water as a combustion byproduct.

But whether those vehicles ever cross over from the niche marketplace to become the mainstay of every garage may depend on how well we can address lingering technical and infrastructure hurdles that stand in the way of their widespread use. One of these is the fuel tank — how do you engineer them so that they can be more like gasoline tanks, which are relatively safe, easy to fill, carry you hundreds of miles and can be refueled again and again with no loss of performance?

This week in the journal Applied Physics Letters, from AIP Publishing (“Size-dependent mechanical properties of Mg nanoparticles used for hydrogen storage”), a team of researchers in the United States and China has taken a step toward that solution. They describe the physics of magnesium hydride, one type of material that potentially could be used to store hydrogen fuel in future automobiles and other applications. Using a technique known as in situ transmission electron microscopy, the team tested different sized nanoparticles of magnesium hydride to gauge their mechanical properties and discovered lessons on how one might engineer the nanoparticles to make them better.

“Smaller particles have better mechanical properties, including better plastic stability,” said Qian Yu, the lead author on the paper. “Our work explained why.”

Yu is affiliated with Zhejiang University in Hangzhou, China; the University of California, Berkeley and Lawrence Berkeley National Laboratory.

Other collaborators on the work are affiliated with the University of Michigan in Ann Arbor; General Motors Research and Development Center in Warren, Michigan; and Shanghai Jiaotong University in Shanghai, China.

The Problem of Storing Hydrogen with Magnesium

Hydrogen storage for automobile engines is still something of an application in search of its technology. We know that the next generation of hydrogen fuel tanks will need to offer greater storage capacities and better gas exchange kinetics than existing models, but we don’t know exactly what it will take to deliver that.

One possibility is to use a material like magnesium hydride, long seen as a promising medium for storage. Magnesium readily binds hydrogen, and so the idea is that you could take a tank filled with magnesium, pump in hydrogen and then pump it out as needed to run the engine.

But this approach is hampered by slow kinetics of adsorption and desorption — the speed with which molecular hydrogen binds to and is released from the magnesium. This is ultimately tied to the how the material binds to hydrogen at the molecular level, and so in recent years researchers have sought to better engineer magnesium to achieve better kinetics.

Previous work had already shown that smaller magnesium nanoparticles have better hydrogen storage properties, but nobody understood why. Some thought it was primarily the greater overall magnesium surface area within the tank realized by milling smaller particles. But Yu and colleagues showed that it is also highly related to how the particles respond to deformation during cycles of fueling and emptying the tank.

Fuel cycles in a hydrogen tank introduce tremendous internal changes in pressure, which can deform the particles, cracking or degrading them. Smaller particles have greater plastic stability, meaning that they are more able to retain their structure even when undergoing deformation. This means that the smaller, more plastic magnesium nanoparticles can retain their structure longer and continue to hold hydrogen cycle after cycle.

But it turns out that in addition to greater plastic stability, the smaller particles also have less “deformation anisotropy” — a measure of how the magnesium nanoparticles all tend to respond, uniformly or not, across the entire tank. Deformation anisotropy is strongly reduced at nanoscales, Yu said, and because of this, smaller magnesium nanoparticles have more homogeneous dislocation activity inside, which offer more homogenously distributed diffusion path for hydrogen.

This suggests a path forward for making better hydrogen storage tanks, Yu said, by engineering them specifically to take advantage of greater homogeneous dislocation. Next they plan to do similar studies on hydrogen storage materials as they undergo fuel cycling, absorbing and desorbing hydrogen in the process.

COLUMBUS, Ohio – Nanoparticles packed with a clinically used chemotherapy drug and coated with an oligosaccharide derived from the carapace of crustaceans might effectively target and kill cancer stem-like cells, according to a recent study led by researchers at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James). Cancer stem-like cells have characteristics of stem cells and are present in very low numbers in tumors. They are highly resistant to chemotherapy and radiation and are believed to play an important role in tumor recurrence. This laboratory and animal study showed that nanoparticles coated with the oligosaccharide called chitosan and encapsulating the chemotherapy drug doxorubicin can target and kill cancer stem-like cells six times more effectively than free doxorubicin.

“Our findings indicate that this nanoparticle delivery system increases the cytotoxicity of doxorubicin with no evidence of systemic toxic side effects in our animal model,” says principal investigator Xiaoming (Shawn) He, PhD, associate professor of Biomedical Engineering and a member of the OSUCCC – James Translational Therapeutics Program.

“We believe that chitosan-decorated nanoparticles could also encapsulate other types of chemotherapy and be used to treat many types of cancer.”

This study showed that chitosan binds with a receptor on cancer stem-like cells called CD44, enabling the nanoparticles to target the malignant stem-like cells in a tumor.

The nanoparticles were engineered to shrink, break open, and release the anticancer drug under the acidic conditions of the tumor microenvironment and in tumor-cell endosomes and lysosomes, which cells use to digest nutrients acquired from their microenvironment.

He and his colleagues conducted the study using models called 3D mammary tumor spheroids (i.e., mammospheres) and an animal model of human breast cancer.

The study also found that although the drug-carrying nanoparticles could bind to the variant CD44 receptors on cancerous mammosphere cells, they did not bind well to the CD44 receptors that were overexpressed on noncancerous stem cells.

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Funding from an American Cancer Society Research Scholar Grant (No. 120936-RSG- 11-109-01-CDD) and a Pelotonia postdoctoral fellowship supported this research.

Other researchers involved in this study were Wei Rao, Hai Wang, Jianfeng Han, Shuting Zhao, Jenna Dumbleton, Pranay Agarwal, Jianhua Yu and Debra L. Zynger of Ohio State; Wujie Zhang of Milwaukee School of Engineering; Gang Zhao of University of Science and Technology of China; and Xiongbin Lu of The University of Texas MD Anderson Cancer Center.

The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute strives to create a cancer-free world by integrating scientific research with excellence in education and patient-centered care, a strategy that leads to better methods of prevention, detection and treatment. Ohio State is one of only 41 National Cancer Institute (NCI)-designated Comprehensive Cancer Centers and one of only four centers funded by the NCI to conduct both phase I and phase II clinical trials. The NCI recently rated Ohio State’s cancer program as “exceptional,” the highest rating given by NCI survey teams. As the cancer program’s 306-bed adult patient-care component, The James is a “Top Hospital” as named by the Leapfrog Group and one of the top cancer hospitals in the nation as ranked by U.S.News & World Report.

What will the 21st century development professional look like? What skills will they need? How will they measure success? How will funding change in the next 10 years?

These questions, and more, were asked of more than 1,000 development professionals in a survey conducted by Devex, in partnership with PSI and the US Global Development Lab at USAID. And the results were illuminating.

For example, sustainability was rated as the most important approach in which to be proficient according to development professionals. Capacity-building, community-based approaches, data-driven and evidence-based programming and innovation followed.

When you download the full report, you’ll discover:

What types of development workers will be valued in the future: integrators, specialists, generalists or disrupters.

How development professionals believe aid will be invested in the future.

Whether aid workers believe they can keep working with a single funder or will need to work with a diverse range.

What industry sectors future aid workers will come from.

How the tools of the trade will change.

What skills from the technology sector are most likely to be integrated in development work (i.e., human-centered design, market-based approaches, crowd-sourcing solutions, gamification).

Like this:

Alexium [ASX:AJX] [OTCQX:AXXIY] is a Perth-based chemical development company with offices in South Carolina.

This morning, they announced a deal that will see them supply US military forces with leading edge flame retardant fabrics.

Alexium has developed a chemical called Alexiflam™. It’s used as a fabric treatment, to make that fabric flame retardant. It’s marketed under different names, depending on which fabric it’s meant for. Ascalon™ is for nylon, Nycolon™ is for nylon-cotton blend fabrics, and Nuvalon™ is for poly-cotton blends. The exact way it works is a bit hush hush, for obvious reasons, including the fact that they supply the military. But if you have a look at their US patent application, the abstract says:

‘An enhanced protective cover includes a top and bottom textile layer and an air permeable, moisture-vapor-transmissive, expanded polytetrafluoroethylene membrane layer located between the two textile layers…The protective cover also includes a top layer coating or fibre treatment of a nano-ceramic material designed to increase the durability of the cover.

…Alternatively, the upper layer of the protective cover may incorporate ceramic coated fibers or ceramic co-extruded fibers, or carbon nanotubes. The protective cover may also feature a fire resistant application. The top textile layer may also include a permanent, highly breathable and highly durable electro-static discharge feature added to the inside of the layer by laying down a carbon based printed pattern on the inside of the layer.’

They’ve also got an Australian patent, which was granted in 2012. This patent explains how the coating sticks to the fabric. It’s pretty dense reading, but you can check it out here.

So basically, they’ve got a very broad, very detailed patent application to cover fabric treatments which create multi-layered protection. The ‘durability’ thing is part of what the military is after. They don’t want anything that’s easily scratched, melted, or transferred onto other surfaces.

Alexium orders to ship Alexiflam™ to Greenwood Mills in huge quantities. Greenwood Mills is a 115-year old company that makes fabrics for the United States Military, amongst other things.

Alexium already has strong links with the US military. For example, in December last year, they announced that they’d got a contract to make a new and improved flame resistant uniform for the US Department of Defense (DoD). In 2013, tests at a DoD-sanctioned facility showed an Alexium product (‘Cleanshell’) effectively repels live chemical warfare agents like sarin gas and mustard gas. That same year, they won a contract to supply the US Marines to develop fire-retardant fabric treatments. Other contracts came before that. In fact, Alexium has a whole affiliate — Alexium Government Solutions — to deal with military contracts.

But this deal is especially important. The president of Alexium, Dirk Van Hyning, explained why. He said that ‘Whilst we have a strong and healthy business in the commercial sector, the sheer size of the Defense market and the fact that our chemistries clearly fit with the stringent performance requirements for military grade FR [flame retardant] fabrics, makes the Defense sector another strong market for Alexium both in the US and internationally. This new customer, with operations in the Defense sector, is a key part of that overall strategy.’

Alexium CEO Nicholas Clark thinks it’ll also be good for their penetration into the commercial market. Greenwood Mills also makes things like denim for big American brands including Levi Strauss, Abercrombie & Fitch [NYSE:ANF], and Hollister.

So there you go — in a few years, you could be wearing military-grade super-jeans that can stand up to chemical warfare and make your bum look good.

Clark said that ‘This new customer shows not only the continuing growth in the range and size of our sales but also the increasing rate at which new orders are being received as the market in both the commercial and defense sectors become increasingly aware of the performance and cost benefits of our award winning environmentally friendly FR solutions.’

Graphene Week 2015 was awash with outstanding research results, but one presentation created quite a stir at this Graphene Flagship conference. To a stunned audience, Robert Roelver of Stuttgart-based engineering firm Bosch reported on June 25, 2015, that company researchers, together with scientists at the Max-Planck Institute for Solid State Research, have created a graphene-based magnetic sensor 100 times more sensitive than an equivalent device based on silicon.

Bosch sensor portfolio

Bosch has long been involved in sensor technology, notably in the automotive sector. In 2008, the company expanded beyond its pressure, acceleration and gyroscopic motion sensors, to geomagnetic, temperature, humidity, air quality and sound pressure devices, including for use in consumer electronics devices such as mobile phones. Roelver noted that Bosch is the world’s number one supplier of microelectromechanical sensors, with €1bn in sales.

Bosch looks at graphene

Interested in whether graphene could enable new applications and improved sensor performance, Bosch has been investigating the use of the two-dimensional material in its pressure, magnetic, humidity, gas and sound pressure devices. The first step was to look at fabrication methods.

Top-down approaches to graphene device fabrication such as mechanical and chemical exfoliation would not work on a commercial scale, so Bosch focused instead on bottom-up techniques such as the thermal decomposition of silicon carbide, and chemical vapor deposition onto metal surfaces. The latter is certainly suited to mass production, and the former possibly so.

Roelver cautioned that graphene-based sensor applications will require 5-10 years before they can compete with established technologies. This is due to the current lack of large-scale wafer-based and transfer-free synthesis techniques.

A graphene-based magnetic sensor

Various substrates were considered by the Bosch and Max-Planck researchers, who in the case of their magnetic sensor settled on hexagonal boron nitride. This is for reasons of both cost and technical performance.

Bosch’s magnetic sensors are based on the Hall effect, in which a magnetic field induces a Lorentz force on moving electric charge carriers, leading to deflection and a measurable Hall voltage. Sensor performance is defined by two parameters: (1) sensitivity, which depends on the number of charge carriers, and (2) power consumption, which varies inversely with charge carrier mobility. It is high carrier mobility that makes graphene useful in such applications, and the results achieved by the Bosch-led team confirm this.

Comparing and contrasting materials, Roelver in his Graphene Week presentation showed that the worst case graphene scenarios roughly match a silicon reference. In the best case scenario, the result is a huge improvement over silicon, with much lower source current and power requirements for a given Hall sensitivity. In short, graphene provides for a high-performance magnetic sensor with low power and footprint requirements.

Graphene sensor 100 times more sensitive

In terms of numbers, the remarkable result shown by Roelver centered on a direct comparison between the sensitivity of a silicon-based Hall sensor with that of the Bosch-MPI graphene device. The silicon sensor has a sensitivity of 70 volts per amp-tesla, whereas with the boron nitride and graphene device the figure is 7,000. That is a jaw-dropping two orders of magnitude improvement, hence the reaction in the conference hall.

After summarizing this stunning research result, Roelver concluded on a high note, stressing that Bosch takes graphene very seriously indeed as a future commercial technology.

“We are pleased to see that Graphene Week has been chosen as the forum to disclose such an important technological milestone,” says Andrea Ferrari, chairman of the Executive Board of the Graphene Flagship. “Bosch’s call for large-area integration of graphene into industrial processes fully matches and validates the flagship’s planned investments in this critical area for the mass production of devices.”

Swarms of microscopic, magnetic, robotic beads could be scrubbing in next to the world’s top vascular surgeons—all taking aim at blocked arteries. These microrobots, which look and move like corkscrew-shaped bacteria, are being developed by mechanical engineers at Drexel University as a part of a surgical toolkit being assembled by the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea.
MinJun Kim, PhD, a professor in the College of Engineering and director of the Biological Actuation, Sensing & Transport Laboratory (BASTLab) at Drexel, is adding his team’s extensive work in bio-inspired microrobotics to an $18-million international research initiative from the Korea Evaluation Institute of Industrial Technologies (KEIT) set on creating a minimally invasive, microrobot-assisted procedure for dealing with blocked arteries within five years.

spirochete microswimmer

Drexel’s microswimmer robots (bottom) are modeled, in form and motion, after the spiral-shaped bacteria, Borrelia burgdorferi (top), that cause Lyme Disease.

DGIST, a government-funded research entity in Daegu, South Korea, is the leader of the 11-institution partnership, which includes some of the top engineers and roboticists in the world. Drexel’s team, the lone representatives from the United States, is already well on its way to tailoring robotic “microswimmer” technology for clearing arteries.

“Microrobotics is still a rather nascent field of study, and very much in its infancy when it comes to medical applications,” Kim said. “A project like this, because it is supported by leading institutions and has such a challenging goal, is an opportunity to push both medicine and microrobotics into a new and exciting place.”

Kim’s microswimmers are chains of three or more iron oxide beads, rigidly linked together via chemical bonds and magnetic force. These chains are small enough­­—on the order of nanometers—that they can navigate in the bloodstream like a tiny boat. The beads are put in motion by an external magnetic field that causes each of them to rotate. Because they are linked together, their individual rotations cause the chain to twist like a corkscrew and this movement propels the microswimmer.

microswimmer device

Using magnetic fields (visual representation at right) generated by an electromagnetic device (left) Drexel engineers are able to control the movement of their micro-swimmer robots.

By controlling the magnetic field, Kim can direct the speed and direction of the microswimmers. The magnetism involve also allows the researchers to join separate strands of microswimmers together to make longer strings, which can then be propelled with greater force.

This research, which was recently reported in the Journal of Nanoparticle Research (“Minimal geometric requirements for micropropulsion via magnetic rotation”), is one of the reasons Kim’s lab was chosen for the ambitious project.

“Our magnetically actuated microswimmer technology is the perfect fit for this project,” Kim said. “The microswimmers are composed of inorganic biodegradable beads so they will not trigger an immune response in the body. And we can adjust their size and surface properties to accurately deal with any type of arterial occlusion.”

Kim’s inspiration for using the robotic swimmers as tiny drills actually came from a malicious bacterium that wreaks havoc inside the body by doing just that—burrowing through healthy tissue. Borrelia burgdorferi, the bacteria that causes Lyme’s Disease, is classified by its spiral shape, which enables both its movement and the resultant cellular destruction.

DGIST researchers are planning to harness this behavior in the microswimmmers to lead the way for a vascular probe by loosening the arterial plaque that is causing the blockage.

The probe, which looks like a tiny drill, is being designed by Bradley Nelson from ETH Zurich, a pioneer in the field of microrobotic surgery. The team’s plan is to use a catheter to deliver the microswimmers and the drill directly to the blocked artery. From there, the swimmers would push their way into the blockage, then the drill would clear it completely.

Once flow is restored in the artery, the microswimmer chains could disperse and be used to deliver anti-coagulant medication directly to the effected area to prevent future blockage.
Multiple robot control of 3 bead achiral microswimmers.

This procedure could supplant the two most common methods for treating blocked arteries: stenting and angioplasty. Stenting is a way of creating a bypass for blood to flow around the block by inserting a series of tubes into the artery, while angioplasty pushes out the blockage by expanding the artery with help from an inflatable probe.

“Current treatments for chronic total occlusion are only about 60 percent successful,” Kim said. “We believe that the method we are developing could be as high as 80-90 percent successful and possibly shorten recovery time.”

Samsung’s team used silicon anodes in lieu of graphite ones; an approach many efforts in this space have taken. The challenge here though is that the silicon can expand or contract during the battery charging and discharging cycles.

To counter that, Samsung’s team created a process to grow graphene cells directly on the silicon in layers that can adjust to allow for the silicon’s expansion:

“The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l-1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries.”

While the technology sounds promising, keep in mind that this is just a research project. Any commercial implementation won’t happen quickly, so for now, you’ll have to keep plugging in that phone, tablet or watch every night.

A swarm of small satellites could give critical infrastructure an Internet connection that never goes down.

By A. Rosenblum

WHY IT MATTERS

Being able to collect data in emergency situations where conventional networks are cut off could be widely useful.

A rendering showing compact communications satellites in relatively low orbit; they could help provide data connections to critical infrastructure.

Anthony Previte, CEO of the space company Terran Orbital, was set on the path to his company’s latest project by a nurse he encountered amid the chaos of 9/11, one block north of Ground Zero.

She was running frantically down the street because the nearby hospital had run out of fuel oil. With most cell-phone batteries depleted and landlines knocked out, the only way to call for more was on foot. Previte got to thinking that important equipment like generators should have ways to communicate anytime, even after a disaster. Today he’s working to make that possible by launching multiple constellations of “nano satellites” designed to provide small, battery-powered sensors with a cheap data connection that never goes down.

Previte says his system will have many civilian and commercial applications and save lives in the wake of natural disasters or terrorist attacks. “If every generator has a sensor on it that reports back to a satellite, then whoever is in charge—FEMA, the government, the military—can move fuel around, with intelligent decisions,” he says.

More and more commercial and industrial equipment is becoming connected to data networks so they can be managed more efficiently, forming what’s known as the Internet of things. Terran’s always-on connections might make that approach more dependable.

Satellite Internet connections available today are mostly targeted at people, not machines, and they’re expensive. They use large satellites parked in geostationary orbits roughly 36,000 kilometers over the equator, meaning that significant energy is required to reach them with a signal from the ground.

Terran is launching small satellites that orbit at only 600 kilometers. That lower altitude makes it practical for low-powered, even disposable, sensors to use a satellite data link, says Previte.

The connection is designed to be more reliable than it is fast. The U.S. army is to use Terran sensors to track vehicles and troops that transmit at tens of kilobytes per second. But Terran expects lower-powered sensors to send up data at about a tenth that speed.

In addition to aiding in disaster relief and tracking shipping containers, planes, and boats, Previte envisions the sensors being used for environmental monitoring. For example, they could be dropped out of a helicopter or drone into a growing oil spill, or onto an active volcano to track lava flows. Terran anticipates significant interest from farmers, who could place sensors in fields or even around the necks of cows.

Previte estimates that Terran can build the disposable, low-powered sensors in bulk for roughly $80 each. Customers will pay a subscription on top of that for their connections. Terran will also sell complete satellites to customers who want the exclusive use of one. “It used to be $400 million for a satellite,” says Previte. Terran will be able to offer them for figures in the low millions of dollars, he says.

In addition to its deal with the U.S. Army, the company says it already has commercial clients, but none that are prepared to disclose their relationship publicly. Deploying a constellation of nano satellites requires 18 to 36 months of lead time, and these companies want to surprise the competition, says Previte.

Terran, which serves as a consultant to integrate satellite payloads and helps with mission control operations, will say that it supported the launch of nine satellites in 2014 and 10 so far this year. The company has also built six small satellites from scratch in 2015.

Jordi Puig-Suari, Terran’s chief science officer, is one of two inventors of the CubeSat, a generic blueprint for miniaturized satellites that are typically a cubic liter in size. Different payloads can be installed in a CubeSat using off-the-shelf electronic components (satellites traditionally have custom-built electronics). Further cost savings come from the way the small satellites can be fitted into unused space inside rockets launching larger satellites or space vehicles.

Kerri Cahoy, an assistant professor of aeronautics and astronautics at MIT, said Terran’s model makes it distinct from most satellite companies.

The development of smaller, cheaper satellite technologies in recent years has led many companies to explore new ways of using low Earth orbit (LEO) satellites.

Many focus on remote imaging—for example, to gather regular photos or infrared imagery. But Cahoy says LEO satellites should make a good low-cost communications network. “It sure beats trying to figure out how to connect a large number of distributed ground sensors to a cable or wire-based ground network,” she says. And satellites can more easily cover large swaths of territory than cellular or Wi-Fi networks, which need many base stations.

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A team of Lehigh University engineers have demonstrated a bacterial method for the low-cost, environmentally friendly synthesis of aqueous soluble quantum dot (QD) nanocrystals at room temperature.

Principal researchers Steven McIntosh, Bryan Berger and Christopher Kiely, along with a team of chemical engineering, bioengineering, and material science students present this novel approach for the reproducible biosynthesis of extracellular, water-soluble QDs in the July 1 issue of the journal Green Chemistry (“Biomanufacturing of CdS quantum dots”). This is the first example of engineers harnessing nature’s unique ability to achieve cost effective and scalable manufacturing of QDs using a bacterial process.

Using an engineered strain of Stenotrophomonas maltophilia to control particle size, Lehigh researchers biosynthesized quantum dots using bacteria and cadmium sulfide to provide a route to low-cost, scalable and green synthesis of CdS nanocrystals with extrinsic crystallite size control in the quantum confinement range. The result is CdS semiconductor…

A team of researchers has created a new implantable drug-delivery system using nanowires that can be wirelessly controlled.

The nanowires respond to an electromagnetic field generated by a separate device, which can be used to control the release of a preloaded drug. The system eliminates tubes and wires required by other implantable devices that can lead to infection and other complications, said team leader Richard Borgens, Purdue University’s Mari Hulman George Professor of Applied Neuroscience and director of Purdue’s Center for Paralysis Research.

“This tool allows us to apply drugs as needed directly to the site of injury, which could have broad medical applications,” Borgens said. “The technology is in the early stages of testing, but it is our hope that this could one day be used to deliver drugs directly to spinal cord injuries, ulcerations, deep bone injuries or tumors, and avoid the terrible side effects of systemic treatment…